Polyurethane based pigment dispersants which contain reactive double bonds

Abstract

Polymeric urethane dispersants with solubilizing polymer chains and with reactive carbon to carbon double bonds are described. The reactive double bonds facilitate molecular weight build-up of the dispersant on dispersed particles (enhancing colloidal stability) or enhance the ability of the dispersants to be crosslinked into a matrix material.

1. A polyurethane dispersant comprising a polyurethane backbone and laterally attached solvent-solubilizing: a) polyether chains of poly(C 2-4 -alkylene oxide), b) polyester chains, c) polyacrylic chains, or d) polyolefin chains, or mixtures thereof; and optionally one or more chain terminators wherein on average each dispersant molecule has at least one reactive carbon to carbon double bond in the backbone, the laterally attached solvent solubilizing chains, or the chain terminators, or combinations thereof, further comprising a nitrogen in a non-reactive amine (non-reactive with respect to isocyanates) laterally attached to the polyurethane backbone such that said nitrogen atom is separated by at least two atoms from the closest atom on the backbone and wherein the non-reactive amine is derived from the chemical group consisting of N,N-bis(2-hydroxyethyl)isonicotinamide; 1,1′-{[3-(dimethylamino)-propyl]imino}bis-2-propanol; or the compound 
       
         
           
           
               
               
           
         
       
       formed from the Michael addition of dimethylaminopropylamine and 2-hydroxyethyl acrylate and wherein said non-reactive amine is a tertiary amine, a quaternary ammonium salt, or combinations thereof. 
     
     
       2. The polyurethane dispersant of  claim 1  wherein the polyester, polyether polyacrylate and polyolefin solvent-solubilizing chains contain a terminating C 1-50 -hydrocarbyl group, optionally containing a reactive carbon to carbon double bond. 
     
     
       3. The polyurethane dispersant of  claim 1  wherein the each dispersant molecule on average comprises at least one solvent-solubilizing poly(C 2-4 -alkylene oxide) (polyether) chain. 
     
     
       4. The polyurethane dispersant of  claim 3  wherein the poly(C 2-4 -alkylene oxide) chain is the residue of a polyether which contains two hydroxyl groups at one end of the polyether chain which react with isocyanates and which hydroxyl groups are separated by not less than 5 atoms. 
     
     
       5. The polyurethane dispersant of  claim 1  wherein the polyester solvent-solubilizing chain is the residue of a polyester which contains two hydroxyl groups at one end of the polyester chain which react with isocyanates and which hydroxyl groups are separated by from 5 to 17 atoms. 
     
     
       6. The polyurethane dispersant of  claim 1 , wherein the solvent-solubilizing polyether chain contains the residue of a compound of formula 1 
       
         
           
           
               
               
           
         
         wherein
 R is C 1-20 -hydrocarbyl group; 
 
         R 1  is hydrogen, methyl or ethyl of which less than 60% is hydrogen; 
         R 2  and R 3  are each, independently, C 1-8 -hydroxyalkyl; 
         Z is C 2-4 -alkylene; 
         X is —O— or —NH—;
 Y is the residue of a polyisocyanate; 
 m is from 5 to 150; 
 p is from 1 to 4; and 
 q is 1 or 2. 
 
       
     
     
       7. The polyurethane dispersant according to  claim 1  wherein the solvent-solubilizing polyether chain contains the residue of a compound of formula 2 
       
         
           
           
               
               
           
         
         wherein
 R is C 1-20 -hydrocarbyl group; 
 R 1  is hydrogen, methyl or ethyl of which less than 60% is hydrogen; 
 R 4  is an isocyanate reactive organic radical; 
 
         R 5  is hydrogen or an isocyanate-reactive organic radical; 
         Z is C 2-4 -alkylene 
         m is from 5 to 150; and 
         n is 0 to 1. 
       
     
     
       8. The polyurethane dispersant of  claim 1  wherein the solvent-solubilizing polyether chain contains the residue of a compound of formula 3 
       
         
           
           
               
               
           
         
         wherein 
         R is C 1-20 -hydrocarbyl group; 
         R 1  is hydrogen, methyl or ethyl of which less than 60% is hydrogen; 
         W is C 2-6 -alkylene; and 
         m is from 5 to 150. 
       
     
     
       9. The polyurethane dispersant of  claim 1  wherein the solvent-solubilizing polyester side chain is the residue of a compound of formula 6
   R 9 O((O)C-A-O) m H  6
 
 wherein 
 R 9  is C 1-50 -hydrocarbyl group; 
 A is C 1-26 -alkylene and/or C 2-26 -alkenylene; and 
 m is from 5 to 150. 
 
     
     
       10. The polyurethane dispersant according to  claim 1  comprising a polyurethane backbone and at least one attached solvent-solubilizing polyester side chain. 
     
     
       11. The polyurethane dispersant as claimed in  claim 10  wherein said solvent solubilizing polyester side chain is obtained from a hydroxy carboxylic acid or lactone thereof containing from 1 to 26 carbon atoms, including mixtures thereof. 
     
     
       12. The polyurethane dispersant of  claim 11  wherein said solvent solubilizing polyester side chain is obtained from the lactone and said lactone comprises ε-caprolactone or δ-valerolactone. 
     
     
       13. The polyurethane dispersant of  claim 10  wherein the polyurethane dispersant has polyurethane backbone and attached solvent-solubilizing polyacrylate which further comprises from 10 to 180 milliequivalents of an acid or amino group, including salts thereof for each 100 g dispersant. 
     
     
       14. The polyurethane dispersant of  claim 1 , wherein said dispersant has a polyurethane backbone portion that is linear as opposed to the polyurethane backbone portion being branched or non-linear and said solvent-solubilizing chains are laterally attached. 
     
     
       15. The polyurethane dispersant of  claim 1 , wherein said dispersant has a polyurethane backbone portion that is essentially non-linear meaning that the polyurethane backbone contains branches either derived from isocyanate reactants that have more than two isocyanate groups and/or reactants with Zerewitinoff active hydrogen groups that have higher functionality than two when reacted with isocyanates. 
     
     
       16. The polyurethane dispersant of  claim 1  wherein the number-average molecular weight of the polyester, polyether, polyacrylate or polyolefin solvent-solubilizing chain is from 300 to 10,000. 
     
     
       17. The polyurethane dispersant as claimed in  claim 1  wherein the total weight percentage of solvent-solubilizing chains is not less than 5% based on the total weight of the dispersant. 
     
     
       18. A polyurethane dispersant according to  claim 1  wherein the non-reactive amine comprises a quaternary ammonium salt.